XG1200 User's Guide
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All Rights Reserved, Copyright (C) PFU LIMITED 2005
4.1 Basic Switch Functions
This section describes the basic switch functions.
4.1.1 Switching
M
ode
The XG1200 provides the following two switching modes.
Store-and-forward switching mode
After the XG1200 has finished receiving a frame, it checks the FCS (Frame Check Sequence) and performs a validity
check (on packet size, etc.) before forwarding the frame. If the switch receives a frame with an error frame, it discards
it.
Cut-through switching mode
The XG1200 transmits the frame to the destination as soon as the first 64 bytes of the frame are received with no
errors. Since the XG1200 starts transmitting the frame before it has received the entire frame, this mode allows
forwarding at low latency.
To change the switching modes, carry out the following procedures in the administrator EXEC mode.
Command
Task
xg# configure terminal
Switch to global configuration mode.
xg(config)# bridge forward-mode
{cut-through | store-and-forward }
xg(config)# no bridge forward-mode
Select the cut-through (or store-and-forward) for the
switching mode.
xg(config)# exit
Exit to administrator EXEC mode.
4.1.2 MAC Address Table Management
MAC address table is a database used for managing the association between address information and destination ports.
The XG1200 can learn up to 8912 entries of MAC addresses.
MAC address table management
The XG1200 has two management methods for MAC address table management.
−
SVL(Shared VLAN Learning)
The XG1200 learns MAC addresses common to all VLANs. Different VLAN with identical MAC addresses are
treated as identical entries.
−
IVL(Independent VLAN Learning)
The XG1200 learns MAC addresses separately for each VLAN. Identical MAC addresses with different VLANs
are treated as separate entries.
To change the MAC address table management modes, carry out the following procedures in the management EXEC
mode.
Command
Task
xg# configure terminal
Switch to the global configuration mode.
xg(config)# bridge learn-mode { ivl | svl }
xg(config)# no bridge learn-mode
Select IVL or SVL for the MAC address table management
mode.
xg(config)# exit
Exit to administrator EXEC mode.
xg# copy running-config startup-config
Save the current settings of the XG1200 to nonvolatile
memory.
xg# reset
If the MAC address table management mode is changed, the
new setting becomes enables after the XG1200 is restarted.
Dynamic MAC address learning
The XG1200 dynamically learns MAC addresses from a received frame. If MAC addresses are not uploaded for a
period by the aging function, they will be removed frome MAC address table.
To disable the dynamic learning, carry out the following procedures in the administrator EXEC mode.
Command
Task
xg# configure terminal
Switch to global configuration mode.
xg(config)# interface port 1 2 3
xg(config)# interface port range 1 3
Switch to the interface edit mode for the port for which you
want to change the configuration.
In this example, the global interface configuration mode is
selected for ports 1 through 3.
xg(config-if)# suppress-address-learning
xg(config-if)# no
suppress-address-learning
Disable (or enable) the dynamic MAC address learning.
xg(config-if)# exit
Exit to global configuration mode.
xg(config)# exit
Exit to administrator EXEC mode.
